1. Field of the Invention
The present invention relates to a medical suturing apparatus for use in surgical operations on tubular structures in the human body such as the intestine and esophagus.
2. Related Art
In the current practice of surgical operations on tubular structures such as intestine and esophagus, anastomosis is performed with a medical suturing apparatus comprising an operating member, an insertion member extending therefrom, a head disposed at the distal end of the insertion member which has a plurality of U-shaped staples arranged on the circumference, and an anvil disposed in a position opposed to the head for clinching the staples.
Commonly known suturing apparatus are operated as follows: the head and the anvil are inserted into two opposed tubular structures and, after the distance between the head and the anvil is shortened, the staples are expelled and clinched by slots in the opposite surface of the anvil while, at the same time, the excess tissue left inside of the staple line is severed by a cylindrical blade positioned inside of the staple line, whereupon the intended anastomosis is completed.
U.S. Pat. No. 5,392,979 discloses a suturing apparatus which permits the anvil to be attached to or detached from the head with comparative ease but in which the anvil is no longer detachable from the head if the distance between the two members has reached an optimal value for anastomosis. Then, a safety mechanism is released, whereupon it becomes possible to fire the staples. An indicator is used to provide a visual signal for the surgeon to know an optimal value of the head to anvil distance. A similar type of suturing apparatus is described in U.S. Pat. No. 5,205,459.
The suturing apparatus described in the two U.S. patents are of a disposable type, which is different from the device proposed in Unexamined Published Japanese Patent Application (kokai) No. 108347/1980. The latter type consists of an operating member, an insertion member, a staple cartridge and an anvil. The operating member combines with the insertion member to comprise a main body and the staple cartridge and the anvil which are disposed at the distal end of the insertion member are replaced after each surgical operation whereas the main body is usable more than once.
The suturing apparatus described above share the common structural feature that the legs of each staple disposed at the distal end of the insertion member are oriented distally so that they can be ejected in a distal direction.
A problem with the suturing apparatus disclosed in U.S. Pat. Nos. 5,392,979 and 5,205,459 is that even if the anvil is yet to be installed, the safety mechanism is released if the indicator signals an optimal distance for performing anastomosis and the surgeon may inadvertently fire staples, resulting in a waste of the staples or accidental ejecting of the circular blade. In addition, the suturing apparatus described in the two U.S. patents is of a disposable type and it must entirely be discarded after single use. Therefore, the apparatus must be purchased for each surgical operation and this only adds to the running cost of hospitals.
In contrast, the suturing apparatus disclosed in Unexamined Published Japanese Patent Application No. 108347/1980 permits repeated use of the main body by replacing the anvil and the staple cartridge. However, the anvil of this apparatus is of such a construction that it is threadably mounted to the rod at the distal end of the insertion member and, therefore, it is not ideal for handling in surgical operations where simple and quick procedures of replacement are necessary.
Further in addition, the known suturing apparatus for use in anastomotic surgical operations on tubular structures including the three devices described above share the common feature that the legs of staples are oriented distally and that therefore the surgeon cannot check immediately after his surgical operation as to whether the legs of the fired staples have been appropriately clinched; this has made it impossible to assure complete prevention of post-operative complications.